Blocking synchronizing arrangement for motor vehicle-change-speed transmissions

ABSTRACT

A blocking synchronization for motor vehicle change-speed transmissions in which an axially displaceable shifting sleeve cooperates with synchronizing rings that are also axially displaceable and rotatable within limits; the synchronizing rings, in their turn, cooperate by means of blocking surfaces with engaging teeth at the gear, whereby an annular spring guided in the synchronizing ring for producing at the synchronizing ring a force directed toward the shifting sleeve, cooperates with a cone surface at the gear, which cone surface has a considerably steeper inclination in its portion directed toward the shifting sleeve.

{13mm States stem [1 Rommelshausen 1451 July 31,1973

BLOCKING SYNCIIRONIZING ARRANGEMENT FOR MOTOR VEI'IICLE-CHANGE-SPEEDTRANSMISSIONS Giinter Wiirner Rommelshausen, Rommelshausen, GermanyAssignee: Daimler-Benz Aktiengesellschait,

Stuttgart-Unterturkheim, Germany Filed: Dec. 15, 1971 Appl. 190.:208,375

Inventor:

Foreign Application Priority Data Dec. 15, 1970 Germany P 20 61 619.7

US. c1; 192/53 F rm. Cl. F16d 23/06 Field 01 Search 192/53 F ReferencesCited UNITED STATES PATENTS 5/1962 Peras 192/53 F 3,175,412 3/1965 Peras192/53 F Primary Examiner-Allan D. Hermann A ttomey- Craig, Antoneliiand Hill 6 Claims, 3 Drawing Figures A I I VFW 5* l6 PATENTE JUL 3 II975 HUI BLOCKING SYNCHRONIZING ARRANGEMENT FOR MOTORVEHICLE-CHANGE-SPEED TRA-NSMISSKONS The present invention relates to ablocking synchronization for motor vehicle change-speed transmissions,in which an axially displaeeable shifting sleeve cooperates withsynchronizing rings also axially displaceable and limitedly rotatable,which in their turn cooperate by means of blocking surfaces with theengaging teeth at the gear, and in which an annular spring guided ineach synchronizing ring for the production of a force at thesynchronizing ring directed toward the shifting sleeve cooperates with acone surface at the gear.

In blocking synchronizations of the aforementioned type, there existsthe desire to produce a friction force at the synchronizing ring, duringthe beginning of the shifting sleeve movements which is as large aspossible, i.e., as large as possible an abutment force of thesynchronizing ring at the shifting sleeve. This is necessary for thereason to attain an immediate shifting of the synchronizing ring intoits blocking position and to prevent thereby with certainty atearing-through of the shifting sleeve without prior synchronization.

The present invention is concerned with the task to provide a solutionto the described problem. As solution to the underlying problems, thepresent invention is predicated on the general concept to locate infront of the cone surface a threshold, so to speak of, with increasedresistance effect. In particular, the present invention proposes inconnection therewith that this cone surface has a considerably steeperinclination at its portion directed toward the shifting sleeve.

The construction according to the present invention offers the advantagethat during a movement of the shifting sleeve in the engaging direction,the corresponding synchronizing ring initially is practically held fastand is caused to abut with its friction surface at the shifting sleevewith a large force. The synchronizing ring is thereby taken alongimmediately in the direction of rotation and shifts into its blockingposition whereby the shifting sleeve is prevented with certainty from anunintentional passing-through into the engaging position.

Exhaustive tests with the construction of the present invention havedemonstrated that the point or apex angle of the steeper portion of thecone surface should be about three times as large as that of the flatterportion.

Synchronization installations of the aforementioned type exist in theprior art, having an abutment arranged at the gear part for the ringspring in the center position of the shifting sleeve. For such types ofarrangements, the present invention further proposes that the conesurface terminates in the direction toward the shifting sleeve in anannular groove, whose raised and very steep flank disposed in thedirection toward the shifting sleeve forms the abutment whereas theflank passing over into the cone surface forms the steep portion of thecone surface.

Accordingly, it is an object of the present invention to provide ablocking synchronization for motor vehicle change-speed transmissionswhich avoids by simple means the aforementioned shortcomings anddrawbacks encountered in the prior art.

Another object of the present invention resides in a blockingsynchronization for motor vehicle changespeed transmissions in which arelatively large friction force is produced at the synchronizing ringduring the beginning of the shifting sleeve movement.

A further object of the present invention resides in a blockingsynchronization for motor vehicle changespeed transmissions whichassures an instantaneous shifting of the synchronizing ring into theblocking position and thus prevents damage to the shifting sleeve orother parts of the synchronizing mechanism due to the premature movementof the shifting sheeve prior to synchronization.

These and other objects, features and advantages of the presentinvention will become more apparent from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, one embodiment of the present invention,and wherein:

FIG. 1 is a partial longitudinal axial cross-sectional view through ablocking synhronization in accordance with the present invention;

FIG. 2 is a partial cross-sectional view, on an enlarged scale,illustrating the details encircled in dash and dot lines in FIG. 1 anddesignated by reference nu meral ii; and

FIG. 3 is a schematic partial longitudinal axial crosssectional view, onan enlarged scale, and illustrating details of the blocking surface andengaging teeth.

Referring now to the drawing, wherein like reference numerals are usedthroughout the two views to designate like parts, and more particularlyto MG. 1, the shifting sleeve 10 illustrated in this figure cooperateswith two synchronizing rings 11 which engage with radially inwardlydirected extensions 12 (FIGS. 1 and 2) in corresponding apertures orcut-outs (not shown) of a gear rim 13 which is formed at or secured onthe gear body. The gear rim 13 carries the engaging teeth 14. One ringspring 15 is arranged in the extensions 12 of each synchronizing ring11, which cooperates with a cone surface generally designated byreference numeral l6 and provided at the gear rim l3 and which producesa force at the synchronizing ring 11 directed toward the shifting sleeve10.

According to FIG. 2, the cone surface 16 consists of a flatter secondportion 17 and of a considerably steeper first portion 18 which isdirected toward the shifting sleeve 10 and which passes over into agroove 19 for receiving the annular spring 15. The flank 20 of thegroove 19 which is disposed on the side facing the shifting sleeve 10,is raised with respect to the ring spring 15 and has a considerablysteeper inclination so that it can serve as abutment for the ring spring15 and therewith for the synchronizing ring 11 in the center position ofthe shifting sleeve 10. As shown in FIG. 2, the inclination of the flankl8 which is disposed as a threshold, so to speak of, between the groove19 and the flatter part 17 of the cone surface 16, properly speaking isinclined considerably more steeply than the portion 17. The latter, ifcompleted into a full cone, would produce, for example, an apex angle ofabout 32. If one completes the steeper portion 18 into a full cone, thenan apex angle of about would result, i.e., it amounts approximately tothree times the apex angle at the flatter portion 17.

During the movement of the shifting sleeve 10 in the engaging directionat first the ring spring 15 abuts against the steeper portion 18 of thecone surface 16, i.e., a very large abutment force of the synchronizingring 11 at the shifting sleeve is produced thereat. The synchronizingring 11 thereby shifts immediately into its blocking position wherebythe blocking surface 11' (FIG. 3) of conventional construction becomeeffective and prevent a passing-through of the shifting sleeve 10 intothe engaging position until synchronism is realized. During thisoperation, the ring spring 15 remains on the steeper portion 18 of thecone surface 16. Only with synchronism and upon further axial pressureon the shifting sleeve 10, the ring spring 15 can pass over onto theflatter portion 17 of the cone surface 16 whereby exclusively the normalabutment force between synchronizing ring 11 and shifting sleevecontinues to be produced from then on.

While I have shown and described only one embodiment according to thepresent invention, it is understood that the same is not limited theretobut is susceptible of numerous changes and modifications as known tothose skilled in the art, and I therefore do not wish to be limited tothe details shown and described herein but intend to cover all suchchanges and modifications as are encompassed by the scope of theappended claims.

What I claim is:

l. A blocking synchronization for use with motor vehicle change-speedgears and the like comprising:

a gear wheel rotatable about a gear wheel axis,

engaging teeth means on said gear wheel, a shifting sleeve axiallydisplaceable along said axis, synchronizing ring means interposedbetween said gear wheel and shifting sleeve, said synchronizing ringmeans being engageable with said shifting sleeve for displacement alongsaid axis in response to axial displacement of said shifting sleeve,said synchronizing ring means including blocking surface meansengageable with said engaging teeth means to transmit rotational forcesbetween said synchronizing ring means and said gear wheel,

and a ring spring guided in said synchronizing ring means for engagementwith cone surface means provided on said gear wheel for producing aforce directed toward the shifting sleeve in response to movement ofsaid shifting sleeve and synchronizing ring means toward said gearwheel,

wherein the cone surface means includes first and second portions ofdifferent inclinations with said first portion being nearer the shiftingsleeve than the second portion, and wherein said first portion isprovided with a considerably steeper inclination than said secondportion.

2. A blocking synchronization according to claim 1, characterized inthat the apex cone angle of the first portion is about three times aslarge as that of the second portion.

3. A blocking synchronization according to claim 2 further comprising anabutment arranged at the gear wheel for the ring spring when theshifting sleeve is in a central position away from said gear wheel,characterized in that the cone surface means terminates in the directiontoward the shifting sleeve in an annular groove having a raised and verysteep flank disposed in the direction toward the shifting sleeve whichforms said abutment whereas an opposite flank of the annular groovepasses over into the cone surface means to form the first portion of thecone surface means.

4. A blocking synchronization according to claim 3, further comprising asecond gear wheel and associated synchronizing ring means and ringspring arranged at the side of said shifting sleeve opposite saidabovementioned gear wheel and similar to said abovementioned gear wheel,synchronizing ring means and ring spring.

5. A blocking synchronization according to claim 1, further comprisingan abutment arranged at the gear wheel for the ring spring when theshifting sleeve is in a central position away from said gear wheel,characterized in that the cone surface means terminates in the directiontoward the shifting sleeve in an annular groove having a raised and verysteep flank disposed in the direction toward the shifting sleeve whichforms said abutment whereas an opposite flank of the annular groovepasses over into the cone surface means to form the first portion of thecone surface means.

6. A blocking synchronization according to claim 1, further comprising asecond gear wheel and associated synchronizing ring means and ringspring arranged at the side of said shifting sleeve opposite saidabovementioned gear wheel and similar to said abovementioned gear wheel,synchronizing ring means and ring spring.

1. A blocking synchronization for use with motor vehicle changespeed gears and the like comprising: a gear wheel rotatable about a gear wheel axis, engaging teeth means on said gear wheel, a shifting sleeve axially displaceable along said axis, synchronizing ring means interposed between said gear wheel and shifting sleeve, said synchronizing ring means being engageable with said shifting sleeve for displacement along said axis in response to axial displacement of said shifting sleeve, said synchronizing ring means including blocking surface means engageable with said engaging teeth means to transmit rotational forces between said synchronizing ring means and said gear wheel, and a ring spring guided in said synchronizing ring means for engagement with cone surface means provided on said gear wheel for producing a force directed toward the shifting sleeve in response to movement of said shifting sleeve and synchronizing ring means toward said gear wheel, wherein the cone surface means includes first and second portions of different inclinations with said first portion being nearer the shifting sleeve than the second portion, and wherein said first portion is provided with a considerably steeper inclination than said second portion.
 2. A blocking synchronization according to claim 1, characterized in that the apex cone angle of the first portion is about three times as large as that of the second portion.
 3. A blocking synchronization according to claim 2 further comprising an abutment arranged at the gear wheel for the ring spring when the shifting sleeve is in a central position away from said gear wheel, characterized in that the cone surface means terminates in the direction toward the shifting sleeve in an annular groove having a raised and very steep flank disposed in the direction toward the shifting sleeve which forms said abutment whereas an opposite flank of the annular groove passes over into the cone surface means to form the first portion of the cone surface means.
 4. A blocking synchronization according to claim 3, further comprising a second gear wheel and associated synchronizing ring means and ring spring arranged at the side of said shifting sleeve opposite said above-mentioned gear wheel and similar to said above-mentioned gear wheel, synchronizing ring means and ring spring.
 5. A blocking synchronization according to claim 1, further comprising an abutment arranged at the gear wheel for the ring spring when the shifting sleeve is in a central position away from said gear wheel, characterized in that the cone surface means terminates in the direction toward the shifting sleeve in an annular groove having a raised and very steep flank disposed in the direction toward the shifting sleeve which forms said abutment whereas an opposite flank of the annular groove passes over into the cone surface means to form the first portioN of the cone surface means.
 6. A blocking synchronization according to claim 1, further comprising a second gear wheel and associated synchronizing ring means and ring spring arranged at the side of said shifting sleeve opposite said above-mentioned gear wheel and similar to said above-mentioned gear wheel, synchronizing ring means and ring spring. 